The biggest breakthrough came in 1971. Attorney Thomas K. Gilhool represented the Pennsylvania Association for Retarded* Citizens v. Commonwealth of Pennsylvania (PARC v. Commonwealth) in a case that resulted in a landmark decision. The court affirmed the right to education at public expense and due process for children with disabilities. Gilhool used Brown v. Board of Education in his arguments. Twenty-seven federal court cases followed and led to the birth of P. L. 94-142, the most influential law that mandated that right.

PARC v Commonwealth was restricted to all "children with mental retardation*." In the same year, Mills v Board of Education of District of Columbia affirmed the Pennsylvania decision and expanded its application to all children with disabilities.

The GCDD is funded under the provisions of P.L. 106-402. The federal law also provides funding to the Minnesota Disability Law Center, the state Protection and Advocacy System, and to the Institute on Community Integration, the state University Center for Excellence. The Minnesota network of programs works to increase the IPSII of people with developmental disabilities and families into community life.